The present invention relates to a throttle opener for use in controlling the opening of a throttle valve to provide the optimum condition for burning an air-fuel mixture, at a deceleration condition of a vehicle.
When a vehicle incorporating an engine with a carburetor is decelerated, the throttle value is returned to an idle position so that the intake efficiency of the engine is decreased due to the increased negative pressure in an intake manifold. In such a condition misfire is likely to take place thereby discharging a considerable amount of unburned hydrocarbons into the atmosphere. In order to meet recent regulations to control automobile air pollution, it has been proposed to install a throttle valve control such as a throttle positioner so arranged as to electrically detect vehicle speed, thereby actuating a solenoid valve to transmit intermittently the negative pressure in the intake manifold and atmospheric pressure to the actuating diaphragm, thus opening the throttle valve by such a predetermined value as to provide the maximum burning efficiency of fuel. The throttle positioner, however, employs complex and expensive devices including a vehicle speed sensor, a computer, and a vacuum switching solenoid and a diaphragm so as to electrically detect the vehicle speed and control the throttle valve of the vehicle.